Because you get like 8 points in level 14, 5/5 heal is always a good choice.
4 skill points left, you know what makes a priest op? Priest mana draining skill aka word power and survivability with shield.
Spending skill points on tears won't make your priest a great nuker, but yes if you use them on shield it will make you tanky, must spend skill points on word power, it is as important as heal. Word power is something that makes a priest op in PvP
My point is, 200 extra damage is not better than a shield that can absorb higher damage + word power that can drain your target mana.